Using a randomized clinical trial with 3 groups, we will conduct a head-to-head evaluation of two different theoretically-based interventions, SystemCHANGE and CHANGE+, as compared to Usual Care to improve the adoption and maintenance of exercise in older cardiac patients. SystemCHANGE, a novel intervention that focuses on environmental change uses System Improvement strategies to increase exercise, will be compared to CHANGE+ (an intervention based on contemporary cognitive behavioral strategies). Study questions are: (1) Is there a difference between SystemCHANGE, CHANGE+, and Usual Care in exercise adoption when controlling for covariates (age, race, functional capacity, body fat, co- morbidity, muscle or joint pain, exercise experience, home and neighborhood environment, and depression), for individuals following a cardiac rehabilitation program (CRP)? (2) Is there a difference between SystemCHANGE, CHANGE+, and Usual Care in exercise maintenance when controlling for covariates? (3) Do system changes, social support for exercise, problem-solving skills, motivation, health beliefs, and exercise self-efficacy mediate the effects of SystemCHANGE, CHANGE+, or Usual Care on exercise adoption? (4) Do system changes, social support for exercise, problem-solving skills, motivation, health beliefs, and exercise self-efficacy mediate the effects of SystemCHANGE, CHANGE+, or Usual Care on exercise maintenance? (5) What are the economic impacts of the SystemCHANGE and CHANGE+ interventions in terms of health care spending, labor force participation and earnings, and household productivity? Older persons (N=420) recovering from cardiac events will be randomly assigned to the three groups. Measures of exercise adoption and maintenance (# of hours exercised, # of hours exercised in target heart rate zone, # of exercise sessions, # of metabolic equivalents {METS} expended, and whether or not a subject remains exercising) will be taken for 1 year after completion of a CRP using heart rate wristwatch monitors, exercise diaries, and a 7-Day Recall Survey. The effect of covariates also will be assessed. Mechanisms by which the interventions achieve their effects will be determined. Multivariate analyses will examine and compare the effects of the interventions over time. A cost-effectiveness analysis also will be conducted.